This invention relates to the separation of organic compounds from aqueous liquids.
U.S. Pat. No. 2,367,384 describes a process for selectively removing small immiscible amounts of organic oily impurities from water by contacting water containing said impurities with an inert solid having a relatively large surface area and having deposited thereon a cationic surface active bonding agent for said solid and for said impurities, and separating the water from the mixture thus formed, said cationic surface active bonding agent being selected from the group consisting of primary, secondary and tertiary organic amines and quaternary ammonium, phosphonium, arsonium, stibonium and ternary sulfonium organic compounds having at least one aliphatic radical containing at least 8 carbon atoms.
It is also known to separate organic compounds from water by a method in which a mixture of water and the organic compounds is allowed to flow through a column composed of granules of a clay which has been treated with a material which renders the surface of the clay hydrophobic and oleophilic, such a treated clay generally being known as an organophilic cation-modified clay or, briefly, as an "organo-clay" (see British Patent Specification No. 664,830). The clay used as a starting material for preparing an organo-clay is usually selected to provide a high degree of absorbency, and clays of the smectite class, such as montmorillonite, bentonite, hectorite and saponite are most suitable for this purpose. The material used to treat the surface of the clay generally comprises molecules which have both polar, or hydrophilic, groups for effective bonding with the hydrophilic clay surface and non-polar, or oleophilic groups, which will form bonds with the organic impurities which are to be removed. Material which have been found to be particularly suitable for this purpose include primary, secondary and tertiary amines and quaternary ammonium compounds, which contain a hydrocarbon radical having at least 8, and, preferably from about 10 to about 24, carbon atoms.